There's other ways to tease out if someone is "dedicated to reaching a goal" like actually asking them questions about their life, daily routine, accomplishments etc. I think these are much better signals than "this person can implement many sorting algorithms and solve towers of hanoi or the egg drop puzzle without a google search to refresh their memory" with an N=1 sample size used to gauge how reliably they can do that. How many people if asked to do this on a job rather than an interview a year later would then go and implement it from memory without double checking they didn't forget some edge case on stackoverflow?
I know grinding leetcode is fundamentally useless because you will immediately start losing your ability to interview once you get hired. If you don't change jobs within a year you'll need to start studying all that crap again for the next interview.